/<template>
  <div class="le">
      <ul>
          <li v-for="item,index in list" :key="index" 
          :class="{on:activeIndex==index}" 
          @click="changeIndex(index)">{{item.title}}</li>
      </ul>
  </div>
</template>

<script>
export default {
    props:{
        list:Array,
        activeIndex:Number,
    },
    methods: {
        changeIndex(index) {
            this.bus.$emit("changeActive",index);
        },
    },
}
</script>

<style>

.le{
    float: left;
    width: 60px;
    height: auto;
}
li{
    padding: 10px;
       
}
.le
    .on{
        background: red;
    }
</style>